docs: def parse_metadata(self):
          """Parse the INDEX_JSON file and reorganize it as a dictionary of lists."""
  
          all_models = defaultdict(list)
  
          with open(self.metadata_index_json) as f:
              loaded = json.load(f)
  
          for m in loaded['index']:
              all_models[m['uniprot_ac']].append(m)
  
          self.all_models = dict(all_models)